POLICY AND GLOBAL AFFAIRS The National Academies Press Washington, DC March 30, /30/2012 1

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1 POLICY AND GLOBAL AFFAIRS The National Academies Press Washington, DC March 30, /30/2012 1

2 The Study Committee ELLEN D. WILLIAMS, Chair, BP MARVIN L. ADAMS, Texas A&M University LINTON BROOKS, Independent Consultant THEODORE W. BOWYER, Pacific Northwest National Laboratory DONALD D. COBB, Los Alamos National Laboratory (retired) RICHARD L. GARWIN, Thomas J. Watson Research Center, IBM Corporation (emeritus) RAYMOND JEANLOZ, University of California, Berkeley RICHARD MIES, Independent Consultant C. BRUCE TARTER, Lawrence Livermore National Laboratory (emeritus) Subcommittee on Seismology LYNN R. SYKES, Subcommittee Chair, Columbia University HANS HARTSE, Los Alamos National Laboratory PAUL G. RICHARDS, Columbia University GREGORY VAN DER VINK, Terrametrics, LLC WILLIAM R. WALTER, Lawrence Livermore National Laboratory 3/30/2012 2

3 Caveats and Limitations Technical issues only, not policy Current as of early 2011 (limited updating) Public version Findings and recommendations are in bold 3/30/2012 3

4 The Issues Can the U.S. maintain the stockpile without nuclear-explosion testing? How well can the U.S. detect, locate, and identify nuclear explosions? What does the U.S. need to do to sustain the stockpile and the U.S. and international monitoring systems? What kinds of nuclear weapons developments are possible under the CTBT versus under a possible return to unrestricted nuclear testing without the CTBT? 3/30/2012 4

5 Maintaining the Stockpile At the time of the 2002 Report, the Stockpile Stewardship Program (SSP) was in its early stages, and there was uncertainty about maintaining the stockpile in the absence of nuclear-explosion testing. The technical capabilities for maintaining the U.S. stockpile absent nuclear-explosion testing are better now than anticipated by the 2002 Report, with significant intervening accomplishments: Systematic capture of the legacy information from the U.S. nuclear test history Assessment of pit lifetimes of years Petascale facilities for Advanced Simulation and Computing Major SSP facilities including DARHT, MESA and NIF Successful Lifetime Extension Programs (LEPs) for the W87 and W76 For several years before 2011, the surveillance program was not providing the timely data needed: Future assessments of aging effects and other issues will require quantities and types of data that have not been provided by the surveillance program in recent years. In addition to the original LEP approach of refurbishment, sufficient technical progress has been made since the 2002 Report that re-use or replacement of nuclear components can be considered as options for improving safety and security of the warheads. 3/30/2012 5

6 Maintaining the Stockpile Provided that sufficient resources and a national commitment to stockpile stewardship are in place, the committee judges that the United States has the technical capabilities to maintain a safe, secure and reliable stockpile of nuclear weapons into the foreseeable future without nuclear-explosion testing. 3/30/2012 6

7 Monitoring The United States has technical capabilities to monitor nuclear explosions in four environments: Underground, using seismic, radionuclide, and infrasound Underwater, using hydroacousticand seismic Atmosphere, using infrasound, radionuclides, EMP and optical Space, using EMP, optical flash and nuclear radiation Technical capabilities have improved significantly since the time of the 2002 Report, although some operational capabilities are at risk due to uncertain support. Major factors in improved capability include: Completion of the majority of the International Monitoring System (IMS) Xeradionuclide detection capabilities Implementation of regional seismic detection and identification Broader bandwidth, digital seismic stations and arrays Increased in computing power and terabyte data storage 3/30/2012 7

8 Seismic Monitoring Seismology is the most effective technology for monitoring underground nuclear-explosion testing. Seismic monitoring for nuclear explosions is complicated by the great variety of geologic media and the variety and number of earthquakes, chemical explosions, and other non-nuclear phenomena generating seismic signals every day. Technical capabilities for seismic monitoring have improved substantially in the past decade, allowing much more sensitive detection, identification, and location of nuclear events. More work is needed to better quantify regional monitoring identification thresholds, particularly in regions where seismic waves are strongly attenuated. The threshold levels for IMS seismic detection are now well below 1 ktworldwide for fully coupled explosions. In Asia, Europe and North Africa, the IMS detection thresholds are substantially better, at 0.09 to 0.22 kt depending on the regional geology. 3/30/2012 8

9 Monitoring: On-Site Inspection A CTBTO on-site inspection (OSI) would have a high likelihood of detecting evidence of a nuclear explosion with yield greater than about 0.1 kilotons, provided that the event could be located with sufficient precision in advance and that the OSI was conducted without hindrance. 3/30/2012 9

10 Sustaining U.S. Technical Capabilities Sustaining two technical programs is essential U.S. nuclear weapons program U.S. monitoring and verification program Primarily an issue of resources. Concerns: High quality workforce Science, engineering, and technology Weapons production complex Weapons surveillance Radionuclide collection capability Satellite detection capability Monitoring research and development Also concerned with NNSA management of labs 3/30/

11 Sustaining U.S. Technical Capabilities As long as the U.S. sustains its technical competency, and actively engages its nuclear scientists and other expert analysts in monitoring, assessing, and projecting possible adversarial activities, it will retain effective protection against technical surprises. This conclusion holds whether or not the United States accepts the formal constraints of the CTBT. 3/30/

12 CTBT Safeguards Six CTBT safeguards were proposed in We did not attempt a revision but have two recommendations. Without agile production capabilities, it is not possible to promptly correct deficiencies revealed by surveillance or to remanufacture components or weapons when required. The U.S. CTBT safeguards should include the maintenance of adequate production and non-nuclear-explosion testing facilities. There is currently no mechanism that would enable Congress to assess whether the U.S. CTBT safeguards were being fulfilled after entry into force. Under the CTBT, the Administration should prepare an annual evaluation of the ongoing effectiveness of safeguards and formally transmit it to Congress. 3/30/

13 Evasive Nuclear-Explosion Testing I An evader determined to avoid detection would test at levels the evader believes would have a low probability of detection. To reduce detection probability to 10 percent, the test level would have to be approximately 3 times smaller than the 90 percent level. Mine masking is a less credible evasion scenario than it was at the time of the 2002 Report because of improvements in monitoring capabilities. Cavity decoupling becomes increasingly challenging with increasing yield. The experimental basis for quantifying decoupling is limited. For IMS and open monitoring networks, methods of evasion based on decoupling and mine masking are credible only for device yields below a few kilotons worldwide and at most a few hundred tons at well-monitored locations. 3/30/

14 Evasive Nuclear-Explosion Testing II With the inclusion of regional monitoring, improved understanding of backgrounds, and proper calibration of stations, an evasive tester in Asia, Europe, North Africa, or North America would need to restrict device yield to levels below 1 kiloton (even if the explosion were fully decoupled) to ensure no more than a 10 percent probability of detection for IMS and open monitoring networks. The States most capable of carrying out evasive nuclearexplosion testing successfully are Russia and China. Countries with less nuclear-explosion testing experience would face serious costs, practical difficulties in implementation, and uncertainties in how effectively a test could be concealed. In any case, such testing is unlikely to require the United States to return to nuclear-explosion testing. 3/30/

15 Hydronuclear Testing The U.S. historically defined hydronuclear tests as having yields up to 2 kg; the former Soviet Union s definition went up to 100 kg. Hydronuclear tests would be of limited value in maintaining the United States nuclear weapon stockpile in comparison with the advanced tools of the Stockpile Stewardship Program. Based on Russia s extensive history of hydronuclear testing, such tests could be of some benefit to Russia in maintaining or modernizing its nuclear stockpile. However, it is unlikely that hydronuclear tests would enable Russia to develop new strategic capabilities outside of its nuclear-explosion test experience. Given China s apparent lack of experience with hydronucleartesting, it is not clear how China might utilize such testing in its strategic modernization. 3/30/

16 Technical Advances Russia and China are unlikely to be able to deploy new types of strategic nuclear weapons that fall outside of the design range of their nuclear-explosion test experience without several multi-kiloton tests to build confidence in their performance. Such multi-kiloton tests would likely be detectable (even with evasion measures) by appropriately resourced U.S. national technical means and a completed IMS network. Other States intent on acquiring and deploying modern, twostage thermonuclear weapons would not be able to have confidence in their performance without multi-kiloton testing. Such tests would likely be detectable (even with evasion measures) by appropriately resourced U.S. national technical means and a completed IMS network. 3/30/

17 U.S. Nuclear-Explosion Testing? The committee has not been able to identify a potential threat that could arise through undetected nuclear-explosion testing that would require the U.S. to return to nuclear-explosion testing. A technical need for a return to nuclear-explosion testing would be most plausible if the U.S. determined that adversaries nuclear activities required development of weapon types not previously tested. In such a situation, the U.S. could invoke the supreme national interest clause and withdraw from the CTBT. 3/30/

18 Final Thought Threats could arise by clandestine nuclear weapons activity. For instance, a country with no testing experience and a modest industrial base could confidently build and deploy a single-stage, unboostednuclear weapon without any testing, if it had access to sufficient quantities of fissile material. These advances could be made whether or not the CTBT were in force. However, it is highly likely that the United States could counter these threats without returning to nuclear-explosion testing and thus could respond equally well whether or not the CTBT were in force. 3/30/

SEEKING A RESPONSIVE NUCLEAR WEAPONS INFRASTRUCTURE AND STOCKPILE TRANSFORMATION. John R. Harvey National Nuclear Security Administration

SEEKING A RESPONSIVE NUCLEAR WEAPONS INFRASTRUCTURE AND STOCKPILE TRANSFORMATION John R. Harvey National Nuclear Security Administration Presented to the National Academy of Sciences Symposium on: Post-Cold